Thermostat



OctQlS, 1932. J. A. SPENCER 1,883,249

THERMOS TAT Original Filed Oct. 31, 1928 her 12, 1926, I have disclosed 111g an appreciably Patented Oct. 18, 1932 v UNITED STATES OI NEWTON VILLE, MASSACHUSETTS,

PATENT OFFICE ASSIGNOR 1'0 SPENCER THER- OBATION OF MASSA- CHUSETTB rzrannosmr Application filed October 81, 1828, Serial No. 318,214. Renewed October 9,-1830.

, This invention relates to thermostats and particularly to thermostat-s adapted to change shape with great suddenness.

In my Patent 1,448,240, granted March 13, 1923, I have disclosed a bimetal thermostat raving a cupped portion and adapted to change its position with extreme speed. This thermostat has a bimetallic portion having such a shape that the surface is non-developable. In my Patent 1,602,510, granted Octometallic element is maintained in a curved or buckled condition at all times.

With th obtain as desired mechanisms such as switches. My present invention comprises a thermostat is characterized by considerably greater movement of the element in response to heat strains than is the case with a thermostat of equal size and equal temperature dify invention of a non-developable bimetaldisk having portions cut out in such manner as to form non-linear or non-radial spokes provides a thermostatic element havgreat-er movement in response to heat strains than is obtained with a similar uncut he stresses in such a thermostat are similar to the stresses set u in an uncut disk (see my Patent 1,448,240) as well as those set up in the elongated buckled thermostat (see my Patent 1,602,510). Inasmuch as this thermostat has an apprecialy greater movement for a electric'switching mechanism.

or each spoke may be curved with a single a bimetal sna acting thermostat 1n WlllCh an elongated b1- I disk as disclosed in my Patent th the disk;

radius of curvature or ma radii of curvature, or may lie a combination oflinear portions or a combination of linear and non-linear portions, or of like irregular forms. It is clear that vides ties of such a spoke or element.

To retain the member in a cupped shape,

a low temperature coefficient of expansion disposed around the edge thereof to cooperate with stationary contacts. made in accord with this could be used. lVhere substantially greater amplitude of movement of the he invention accordingly comprises the elements and combinations of elements, fea tures 0* construction, and arrangements of which will be indicated in the following claims.

n the accompanying drawing, in which is illustrated one of various possible embodiments of the invention,

- gigure 1 is a plan view of the thermostat an Figure 2 is a sectional view along line 2-2 of Figure 1.

have different Thermostatic units ter outwardly or the reverse.

' that the throw of the .Similar reference characters indicate corresponding parts throughout the several views of the drawing.

Referring now more particularly to the drawing there is represented at numeral 1 a bimetallic member comprising a central portion 2 from which radiate curved or voluted spokes 3. These spokes may take on a variety of forms as pointed out hereinbefore and may either be of uniform width throughout their length or may be tapered either from the cen- To retain the thermostatic member in a cupped plane, a bezel 5 is disposed around the periphery thereof. This bezel 5 is preferably of a metal which has a low coefficient of expansion such as invar steel, and is provided with a slot 6 cut around in the inner edge thereof into which bimetallic member 1 may be sprung. Instead of the provision of the bezel 5 the peripheral retaining means may comprise an integral portion of the disk 1.

So that the curvature of the disk may be adjusted, the bezel 5 is split and provide with lugs 7 and 8, and a screw 9 passing freely and engaging with a threaded through 7 portion in lug 8. Turning of the screw 9 alters the curvature of the disk 1 which accordingly changes the temperatures of operation for the thermostat.

A thermostat of this character will respond to heat strains by snapping from one cuppe shape to a reverse cupped shape. The temperature differential within which the thermostat will snap back and forth is substantially smaller than the temperature differential of the original disk from which it was cut, assuming equal cupped shapes. For a disk to have the same temperature differential as this thermostat, it would be necessary to have the disk flatter, thus reducing the throw of the disk. If the curvature or cupper shape of the disk is made greater to obtain a greater throw, the temperature differential is correspondingly enlarged. If, however, in-

stead of increasing the curvature of such a disk, it be cut out to form curved spokes and then its curvature increased, it will be found thermostat is appreciably greater than the original 'disk while maintaining the original temperature differential characteristic of the disk.

Thus it will be seen that I have devised a snap acting thermostat in' which the throw or movement of the bimetallic member is substantially increased without substantially affecting other thermostatic properties.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above described constructions without departing from the scope of the ind spokes radiating therefrom,

1 the length of said spokes vention, it is intended that all matter contained in the above description or shown in the accomp'anyin drawing shall be interpreted as illustrative and not in a limiting sense.-

I claim 1. A thermostat comprising a bimetallic member lying in a cupped plane, said member having a central portion and voluted spoke elements radiating therefrom.

' 2. A thermostat comprising a bimetallic member lying in a cuppedplane, said member having a central portion, voluted spokes radiating therefrom and a metallic rim retaining the free ends of said spokes.

3. A thermostat comprising a bimetallic member lying in a cupped plane, said member having a central portion, tangentially voluted spokes radiating therefrom and a metallic rim of relatively inexpansible material.

4. A thermostat comprising a-bimetallic member lying in a cupped plane, said member comprising a central portion, non-linear a rim for said bimetallic member and means for adjusting the curvature of the plane in which said bimetallic member lies.

5. A thermostat comprising a bimetallic member lying in a cupped plane, said member including a central having non-linear ortion spokes radiating t erefrom, a rim of relad tively inexpansible material for said bimetallic member and means for adjusting said rim whereby the curvature of the plane in which said bimetallic member lies is varied.

6. A snap-acting thermostatic device comprising a central portion, a peripheral rim portion, and non-radialspokes joining said portions.

7. A thermostatic member comprising a composite, arched sheet, spokes in said sheet, being greater than the distance along the arch from the center of said sheet to its outer boundary.

In testimony whereof, I have signed my named to this spepgication.

HN A. SPENCER. 

